MULTILAYER COLLIMATOR, AND METHOD FOR MANUFACTURING A MULTILAYER COLLIMATOR
A multilayer collimator for a radiation detector comprises a first layer of a first attenuator material and a second layer of a second attenuator material, each having a coincident opening therethrough. The second attenuator material has an atomic mass smaller than that of the first attenuator material. The second layer continues into an extension departing from the plane of said second layer. There is at least one location in said second layer where a normal to the surface of said second layer passes through a part of said first layer and into said extension, for locking said first layer and second layer into an assembled configuration of the multilayer collimator.
The present application claims priority to European Patent Application No. 22169353.4 filed on Apr. 22, 2022. The entire contents of the above-listed application are hereby incorporated by reference for all purposes.
FIELD OF THE DISCLOSUREThe disclosure is generally related to solid-state semiconductor radiation detectors. In particular, the disclosure is related to hardware used to select and shape the incoming radiation that is to hit and enter the actual detector material. The disclosure is also related to methods used to manufacture such hardware, as well as detectors equipped with such hardware.
BACKGROUND OF THE DISCLOSURESolid-state semiconductor radiation detectors are based on the physical phenomenon in which incoming radiation temporarily creates free charges in a semiconductor material. The created free charges may be collected to electrodes and measured, which then allows drawing conclusions about the intensity and/or energy spectrum of the incoming radiation.
While the term “collimator” is often used for parts that shape a beam of radiation by only allowing mutually collimated rays to pass, in a radiation detector such as that in
The generation of such unwanted fluorescence depends on a number of factors, one of which is the material of the collimator. From the manufacturing point of view, most straightforward would be to make the collimator of a single material, such as gold, palladium, or silver. A solid-state semiconductor radiation detector equipped with such a collimator might suit well a measurement of which it is known beforehand that the wavelengths of interest will be far from the characteristic fluorescent wavelengths of the collimator material. However, as the most advantageous possibility would be to provide radiation detectors suitable for as many purposes as possible, it is more desirable to look for solutions in which the amount of interfering fluorescence from the collimator could be minimized altogether.
A known solution is a multilayer collimator 306, an example of which is shown in
A reference document that discloses layered collimators is U.S. Pat. No. 8,835,857. Another reference document U.S. Pat. No. 8,648,313 considers layered screening structures between the substrate package and the cooling element, for keeping fluorescent radiation generated in the cooling element (by energetic radiation that went through the substrate package) from propagating backwards towards the detector crystal. A known drawback of layered collimators like those in
This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
According to a first aspect, a multilayer collimator for a radiation detector comprises a first layer of a first attenuator material of fluorescent X-rays, said first layer having an opening therethrough, and a second layer of a second attenuator material of fluorescent X-rays, said second layer having an opening therethrough coincident with the opening in said first layer. Said second attenuator material has an atomic mass smaller than the atomic mass of said first attenuator material. Said second layer continues into an extension departing from the plane of said second layer, wherein there is at least one location in said second layer where a normal to the surface of said second layer passes through a part of said first layer and into said extension, for locking said first layer and second layer into an assembled configuration of the multilayer collimator.
According to an embodiment, said extension continues along and covers the whole limiting surface around said opening. This involves at least the advantage that the extension may constitute a part of a layered structure the purpose of which is to guard against secondary fluorescent photons that could escape through the walls of the opening.
According to an embodiment, said extension has a first portion continuing from said second layer essentially perpendicular to said first and second layers and a second portion continuing from said first portion on the other side of said first layer than the second layer. This involves at least the advantage that the structure can be formed by using a protruding extension as a central axis, around which one or more annular layers are placed, and thereafter bending a remaining protruding part of the extension outwards and onto the stack of layers to form said second portion.
According to an embodiment, said extension has a portion that continues along at least a part of edges of said opening at an oblique angle against said first and second layers. This involves at least the advantage of a variety of possibilities concerning the three-dimensional geometry of the multilayer collimator.
According to an embodiment, said extension is a first extension and said second layer continues into a second extension along at least a part of outer edges of the multilayer collimator. There can then be at least one location in said second layer where a normal to the surface of said second layer passes through a part of said first layer and into said second extension. This involves at least the advantage that the second extension may add structural strength.
According to an embodiment, the multilayer collimator comprises a third layer of said second attenuator material, said third layer having an opening therethrough coincident with the openings in said first and second layers. Said third layer may be on the other side of said first layer than said second layer. This involves at least the advantage that the second and third layers may be formed through a deposition method.
According to an embodiment, the multilayer collimator comprises more than two layers, at least three of said more than two layers being of materials of different atomic masses. This involves at least the advantage of enhanced attenuation of unwanted fluorescent radiation.
According to an embodiment, said first layer is a centre layer of said more than two layers. The multilayer collimator may then be symmetric, with respect to composition of layers, in relation to the plane of said first layer. This involves at least the advantage that the orientation of the multilayer collimator during assembling is not important.
According to a second aspect, there is provided a solid-state semiconductor radiation detector, comprising at least one multilayer collimator of a kind described above.
According to a third aspect, there is provided a method for manufacturing a multilayer collimator. The method comprises producing a first layer of a first attenuator material of fluorescent X-rays so that said first layer becomes to have an opening therethrough and producing a second layer of a second attenuator material of fluorescent X-rays so that said second layer becomes to have an opening therethrough. Said second attenuator material has an atomic mass smaller than the atomic mass of said first attenuator material. The method comprises also continuing said second layer into an extension along at least a part of the edges of said opening and making the opening in said second layer coincident with the opening in said first layer. The method comprises also locking said first layer and second layer into an assembled configuration of the multilayer collimator by forming at least a part of said extension so that there is at least one location in said second layer where a normal to the surface of said second layer passes through a part of said first layer and into said extension.
According to an embodiment, said locking of said first layer and second layer into said assembled configuration comprises shaping said extension or a part thereof after assembling said first layer and said second layer together. This involves at least the advantage that a relatively simple and straightforward manufacturing methods can be used.
According to an embodiment, said shaping of said extension or a part thereof comprises bending an extremity of said extension onto a side of said first layer opposite to the side that is towards said second layer. This involves at least the advantage that the structure can be formed by using a protruding extension as a central axis, around which one or more annular layers are placed, and thereafter bending a remaining protruding part of the extension outwards and onto the stack of layers to form said second portion.
According to an embodiment, the opening through the first layer is of a larger diameter than the opening through said second layer, and said shaping of said extension or a part thereof comprises expanding said extension or a part thereof against the edge that defines the opening through the first layer. This involves at least the advantage of a variety of possibilities concerning the three-dimensional geometry of the multilayer collimator.
According to an embodiment, said locking of said first layer and second layer into said assembled configuration comprises making said second layer cover at least a majority of two opposite sides of the first layer. This involves at least the advantage of allowing the use of a large selection of manufacturing methods.
According to an embodiment, said second layer is produced by depositing onto said first layer. This involves at least the advantage that the first and second layers may become very tightly bound together already during manufacturing.
The accompanying drawings, which are included to provide a further understanding of the disclosure and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description help to explain the principles of the disclosure. In the drawings:
In the following description, reference is made to the accompanying drawings, which form part of the disclosure, and in which are shown, by way of illustration, specific aspects in which the present disclosure may be placed. It is understood that other aspects may be utilised, and structural or logical changes may be made without departing from the scope of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense, as the scope of the present disclosure is defined be the appended claims.
For instance, it is understood that a disclosure in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa. For example, if a specific method step is described, a corresponding device may include a unit to perform the described method step, even if such unit is not explicitly described or illustrated in the figures. On the other hand, for example, if a specific apparatus is described based on functional units, a corresponding method may include a step performing the described functionality, even if such step is not explicitly described or illustrated in the figures. Further, it is understood that the features of the various example aspects described herein may be combined with each other, unless specifically noted otherwise.
Here, and also in the other embodiments described below, the annular form of the multilayer collimator 510 may be assumed to be that of a regular, circular ring. While collimators in the shape of a regular, circular ring are often used in solid-state semiconductor radiation detectors, any of the multilayer collimators described here could have also some other general shape, such as a square, hexagon, or octagon for example. For acting as a collimator, i.e. in order to effectively allow only a selected portion of incoming radiation to hit a substrate package, the collimator should have an opening therethrough—hence the general designation of the shape being annular.
While an important application of collimators of this kind is in solid-state semiconductor radiation detectors, it should be noted that the same structural principle and manufacturing method may be used for collimators in other kinds of radiation detectors, such as gas-filled proportional counters for example.
The multilayer collimator 510 in
Preferably, but not mandatorily, the layers 502, 503, and 504 are made of attenuator materials that have atomic masses smaller than the atomic mass of the first attenuator material of the first layer 501. Following the common principle in multilayer collimators, the materials of said layers may form a series of consecutively decreasing atomic masses. In general, at least the “second” layer 504 is made of a second attenuator material that has an atomic mass smaller than the atomic mass of the first attenuator material.
In order to keep the relations between generated and attenuated fluorescent radiation wavelengths straightforward, it is preferable to use essentially pure elements as attenuator materials. Essentially pure means in this respect that the material consists of a single element to an extent that is practically achievable at reasonable cost. In such a case it is also relatively unambiguous to characterise the attenuator materials through their atomic masses. In case a layer consists of more than one element, its atomic mass should be considered to mean a characteristic atomic mass that explains a majority of observed fluorescent properties of such a material on the wavelengths of interest. If two or more layers are considered together as a “layer” for the purpose of verbal description, the atomic masses of the materials of both or all such layers should be considered together.
The same layered structure exists also on the inner edge of the collimator, i.e. on the surface that limits the opening at the centre of the annular form. As a difference to the collimator structure described earlier in this text with reference to
Considering the “second” layer 504 in particular, it continues into an extension departing from the plane of the second layer 504. In
In the embodiments of
Following the examples shown above in
Embodiments such as those in
Above it was already mentioned that it is not obligatory to make the extension—the form of which locks the layers together into an assembled configuration of the multilayer collimator—extend all the way along the edge that limits the central opening of the collimator.
Method embodiments for manufacturing a multilayer collimator comprise producing a first layer of a first attenuator material of fluorescent X-rays so that said first layer becomes to have an opening therethrough, and producing a second layer of a second attenuator material of fluorescent X-rays so that said second layer becomes to have an opening therethrough, wherein said second attenuator material has an atomic mass smaller than the atomic mass of said first attenuator material. The method embodiments also comprise continuing said second layer into an extension departing from the plane of said second layer. The opening in said second layer must be made coincident with the opening in the first layer. The method embodiments then comprise locking said first layer and second layer into an assembled configuration of the multilayer collimator by forming at least a part of said extension so that there is at least one location in said second layer where a normal to the surface of said second layer passes through a part of said first layer and into said extension.
If the second layer is made of a malleable material such as aluminium or other metal, the method step of locking the layers into an assembled configuration may comprise shaping said extension or a part thereof after assembling said first layer and said second layer together. The extension may first constitute a straight cylindrical surface, around which the annular first layer (and possible intermediate layers, all having the corresponding annular shape) is placed. The edge of the cylindrically formed extension may then be bent outwards so that it becomes a lip encircling the central opening of the multilayer collimator on top of the stack of layers. Depending on the details of the structure, said method step may contain also other forms of bending an extremity of said extension onto a side of said first layer opposite to the side that is towards said second layer.
In method embodiments that aim at producing multilayer collimators like those of
The method step of locking said first layer and second layer into said assembled configuration may also comprise making said second layer cover at least a majority of two opposite sides of the first layer, like in
The term “fluorescent X-rays” is primarily used in this text to mean X-rays emitted as characteristic “secondary” X-rays from a material that has been excited by being bombarded with high-energy X-rays or gamma rays. Wavelengths of fluorescent X-rays that are commonly used for elemental analysis of chemical substances and compounds vary from the 0.05357 nanometers Kα1 line of cadmium to the 6.76 nanometers Kα line of boron. Also the 11.40 nanometers Kα line of beryllium and the 22.80 Kα line of lithium are sometimes referred to as fluorescent X-rays, although X-rays in general are considered to range from 10 picometers to 10 nanometers.
Any range or device value given herein may be extended or altered without losing the effect sought. Also any embodiment may be combined with another embodiment unless explicitly disallowed.
Although the subject matter has been described in language specific to structural features and/or acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as examples of implementing the claims and other equivalent features and acts are intended to be within the scope of the claims.
It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments. The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages. It will further be understood that reference to ‘an’ item may refer to one or more of those items.
The steps of the methods described herein may be carried out in any suitable order, or simultaneously where appropriate. Additionally, individual blocks may be deleted from any of the methods without departing from the spirit and scope of the subject matter described herein. Aspects of any of the embodiments described above may be combined with aspects of any of the other embodiments described to form further embodiments without losing the effect sought.
The term ‘comprising’ is used herein to mean including the method, blocks or elements identified, but that such blocks or elements do not comprise an exclusive list and a method or apparatus may contain additional blocks or elements.
It will be understood that the above description is given by way of example only and that various modifications may be made by those skilled in the art. The above specification, examples and data provide a complete description of the structure and use of exemplary embodiments. Although various embodiments have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the spirit or scope of this specification.
Claims
1. A multilayer collimator for a radiation detector, comprising:
- a first layer of a first attenuator material of fluorescent X-rays, said first layer having an opening therethrough, and
- a second layer of a second attenuator material of fluorescent X-rays, said second layer having an opening therethrough coincident with the opening in said first layer;
- wherein said second attenuator material has an atomic mass smaller than the atomic mass of said first attenuator material,
- wherein said second layer continues into an extension departing from the plane of said second layer, wherein there is at least one location in said second layer where a normal to the surface of said second layer passes through a part of said first layer and into said extension, for locking said first layer and second layer into an assembled configuration of the multilayer collimator.
2. A multilayer collimator according to claim 1, wherein said extension continues along and covers the whole limiting surface around said opening.
3. A multilayer collimator according to claim 1, wherein said extension has a first portion continuing from said second layer essentially perpendicular to said first and second layers and a second portion continuing from said first portion on the other side of said first layer than the second layer.
4. A multilayer collimator according to claim 1, wherein said extension has a portion that continues along at least a part of edges of said opening at an oblique angle against said first and second layers.
5. A multilayer collimator according to claim 1, wherein:
- said extension is a first extension,
- said second layer continues into a second extension along at least a part of outer edges of the multilayer collimator, wherein there is at least one location in said second layer where a normal to the surface of said second layer passes through a part of said first layer and into said second extension.
6. A multilayer collimator according to claim 3, comprising a third layer of said second attenuator material, said third layer having an opening therethrough coincident with the openings in said first and second layers, and said third layer being on the other side of said first layer than said second layer.
7. A multilayer collimator according to claim 1, wherein:
- the multilayer collimator comprises more than two layers, at least three of said more than two layers being of materials of different atomic masses.
8. A multilayer collimator according to claim 7, wherein:
- said first layer is a centre layer of said more than two layers, and
- said multilayer collimator is symmetric, with respect to composition of layers, in relation to the plane of said first layer.
9. A solid-state semiconductor radiation detector, comprising at least one multilayer collimator according to claim 1 and a detector element of fluorescent X-rays.
10. A method for manufacturing a multilayer collimator, the method comprising:
- producing a first layer of a first attenuator material of fluorescent X-rays so that said first layer becomes to have an opening therethrough,
- producing a second layer of a second attenuator material of fluorescent X-rays so that said second layer becomes to have an opening therethrough, wherein said second attenuator material has an atomic mass smaller than the atomic mass of said first attenuator material,
- continuing said second layer into an extension along at least a part of the edges of said opening,
- making the opening in said second layer coincident with the opening in said first layer, and
- locking said first layer and second layer into an assembled configuration of the multilayer collimator by forming at least a part of said extension so that there is at least one location in said second layer where a normal to the surface of said second layer passes through a part of said first layer and into said extension.
11. A method according to claim 10, wherein said locking of said first layer and second layer into said assembled configuration comprises shaping said extension or a part thereof after assembling said first layer and said second layer together.
12. A method according to claim 11, wherein said shaping of said extension or a part thereof comprises bending an extremity of said extension onto a side of said first layer opposite to the side that is towards said second layer.
13. A method according to claim 11, wherein the opening through the first layer is of a larger diameter than the opening through said second layer, and said shaping of said extension or a part thereof comprises expanding said extension or a part thereof against the edge that defines the opening through the first layer.
14. A method according to claim 10, wherein said locking of said first layer and second layer into said assembled configuration comprises making said second layer cover at least a majority of two opposite sides of the first layer.
15. A method according to claim 14, wherein said second layer is produced by depositing onto said first layer.
Type: Application
Filed: Apr 4, 2023
Publication Date: Oct 26, 2023
Inventors: Jukka Hassi (Espoo), Vesa Kulkki (Espoo), HeiKKi Mikander (Espoo), Tuomas Pylkkaenen (Espoo)
Application Number: 18/295,702